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By Isidor Buchmann, President, Cadex Electronics
Inc.
This email address is being protected from spambots. You need JavaScript enabled to view it.
February 2001

Battery experts agree that the battery, as we know it today,
will remain a ‘weak link’ for the foreseeable future.
Given its relatively short life span, the battery is also the most
expensive and least reliable component of a portable device.

An innovative new approach will be needed to satisfy the
ever-increasing thirst for mobile power. The ideal battery, which
would provide an inexhaustible pool of energy carried in a small
package, is still far from reality. Will this miracle battery be
based on the classic electro-chemical concept, the evolving fuel
cell or some groundbreaking new technology? This answer is
anyone’s guess.

In this article we focus on the emerging fuel cell and examine
its suitability in stationary, mobile and portable applications.
But first we make some general cost comparisons on available power
sources.

Cost of Mobile
Power

Among the common power sources, energy from non-rechargeable
batteries is the most expensive. This cost increases with smaller
battery sizes. Figure 1 reflects the cost per kWh using
non-rechargeable batteries, also referred to as primary
batteries.

Figure 2 evaluates the cost to generate one kilowatt (kW) of
energy by means of a rechargeable battery, combustion engine, fuel
cell and electricity from the utility grid. We take into account
the initial investment, add the fuel consumption and include the
eventual replacement of each system.

Power obtained through the electrical utility grid is most cost
effective. Consumers in industrialized countries pay between $0.05
and 0.10US per kWh. The typical daily energy consumption of a
household is 25 kilowatt-hour (kWh).

Energy
Source

Investment
of equipment to generate 1kW

Lifespan
of equipment before major overhaul or replacement

Cost of fuel
per kWh

Total Costper kWh, incl. fuel, maintenance and equipment
replacement.

NiCd
For portable use

$7,000
based on 7.2V, 1000mAh at $50/pack

1500 h
based on 1C discharge

$0.15
electricity for charging

$7.50

Gasoline Engine
For mobile use

$30
based on $3,000/100kW (134HP)

4000 h

$0.10

$0.14

Diesel
Engine
For stationary use

$40
based on $4,000/100kW (134HP)

5000 h

$0.07

$0.10

Fuel Cell

$3,000 –
7,500

$0.35

For portable
use

2000 h

$0.35

$1.85 –
4.10

For mobile use

4000 h

$0.35

$1.10 –
2.25

For stationary
use

40,000 h

$0.35

$0.45 –
0.55

ElectricityFrom electric grid

All inclusive

All inclusive

0.10

0.10

Figure 2: Cost Comparison to
generate one kilowatt (kW) of energy, taking into account
the initial investment, fuel consumption, maintenance and eventual
replacement of the equipment. The costing information on
the fuel cell is based on current estimates. Lower material costs
and volume production will eventually moderate these costs.

The Fuel Cell

A fuel cell is an electrochemical device, which combines
hydrogen fuel with oxygen to produce electric power, heat and
water. In many ways, the fuel cell resembles a battery. Rather than
applying a periodic recharge, a continuous supply of oxygen and
hydrogen is supplied from the outside. Oxygen is drawn from the air
and hydrogen is carried as fuel in a pressurized container. As
alternative fuel, methanol, propane, butane and natural gas can be
used.

The fuel cell does not generate energy through burning; rather,
it is based on an electrochemical process. There are little or no
harmful emissions. The only release is clean water. In fact, the
water is so pure that visitors to Vancouver’s Ballard Power
Systems drank clear water emitted from the tailpipes of buses
powered by a Ballard fuel cell.

The fuel cell is twice as efficient in energy conversion through
a chemical process than through combustion. Hydrogen, the simplest
element consisting of one proton and one electron, is plentiful and
is exceptionally clean as a fuel. Hydrogen makes up 90 percent of
the composition of the universe and is the third most abundant
element on the earth’s surface. Such a wealth of fuel would
provide an almost unlimited pool of energy at relatively low cost.
But there is a price to pay. The fuel cell core (or stack), which
converts oxygen and hydrogen to electricity, is expensive to build
and maintain.

Hydrogen must be carried in a pressurized bottle. If propane,
natural gas or diesel is used, a reformer is needed to extract the
hydrogen. Reformers for PEMs are bulky and expensive. They start
slowly and purification is required. Often the hydrogen is
delivered at low pressure and additional compression is required.
Some fuel efficiency is lost and a certain amount of pollution is
produced. However, these pollutants are typically 90 percent less
than what comes from the tailpipe of a car.

The fuel cell concept was developed in 1839 by Sir William Grove, a
Welsh judge and gentleman scientist. The invention never took off,
partly because of the success of the internal combustion engine. It
was not until the second half of the 20th century when scientists
learned how to better utilize materials such as platinum and
Teflon™, that the fuel cell could be put to practical use.

A fuel cell can be thought of as electrolysis in reverse, using two
electrodes separated by an electrolyte. Hydrogen is presented to
the negative electrode (anode) and oxygen to the positive electrode
(cathode). A catalyst at the anode separates the hydrogen into
positively charged hydrogen ions and negatively charged electrons.
On the PEM system, the hydrogen is catalyzed; the smaller protons
migrate across the membrane to the cathode where they combine with
oxygen to produce water and heat. The electrodes pick up the
electrons to produce an electric current. A single fuel cell
produces 0.6 to 0.8V under load. Several cells are connected in
series to obtain higher voltages.

The first practical application of the fuel cell system was made
in the 1960s during the Gemini space program, when this power
source was favored over nuclear or solar power. The fuel cell,
based on the alkaline system, generated electricity and
produced the astronauts’ drinking water. Commercial
application of this power source was prohibitive at that time
because of the high cost of materials. In the early 1990s,
improvements were made in stack design, which led to increased
power densities and reduced platinum loadings at the
electrodes.

High cost did not hinder Dr. Karl Kordesch, the
co-inventor of the alkaline battery, to convert his car to an
alkaline fuel cell in the early 1970s. Dr. Kordesch drove the car
for many years in Ohio, USA. The hydrogen tank was placed on the
roof and the trunk was utilized to store the fuel cell and back-up
batteries. According to Dr. Kordesch, there was enough room for
four people and a dog.

Type of fuel cells — Several variations of fuel
cell systems have emerged. The most common are the previously
mentioned and most widely developed PEM System using a polymer
electrolyte. This system is aimed at vehicles and portable
electronics. Several developers are also targeting stationary
applications. The Alkaline System, which uses a liquid electrolyte,
is the preferred fuel cell for aerospace applications, including
the Space Shuttle. Molten Carbonate, Phosphoric Acid and Solid
Oxide Fuel Cells are reserved for stationary applications, such as
power generating plants for electric utilities. Among these
stationary systems, the Solid Oxide is the least developed but has
received renewed attention due to breakthroughs in cell material
and stack designs. Figure 3 compares the most common fuel cell
systems in development.

Figure 3: Advantages and
disadvantages of the various fuel cell systems.
The PEM is the most widely
developed system today.

The PEM system allows compact designs and achieves a high energy
to weight ratio. Another advantage is a quick start-up when
hydrogen is applied. The stack runs at a relatively low temperature
of about 80°C (176°F). The efficiency is approximately
50 percent. (In comparison, the internal compaction motor has
an efficiency of about 15%).

The limitations of the PEM system are high manufacturing costs
and complex water management issues. The stack contains hydrogen,
oxygen and water. If dry, the input resistance is high and water
must be added to get the system going. Too much water causes
flooding.

The PEM fuel cell has a limited temperature range. Freezing
water can damage the stack. Heating elements are needed to keep the
stack within an acceptable temperature range. The warm-up is slow
and the performance is poor when cold. Heat is also a concern if
the temperature rises too high.

The PEM fuel cell requires heavy accessories. Operating
compressors, pumps and other apparatus consumes 30 percent of the
energy generated. The PEM stack has an estimated service life of
4000 hours if operated in a vehicle. The relatively short life span
is caused by intermittent operation. Start and stop conditions
induce drying and wetting, which contributes to membrane stress. If
run continuously, the stationary stack is good for about 40,000
hours. The replacement of the stack is a major expense.

The PEM fuel cell requires pure hydrogen. There is little
tolerance for contaminates such as sulfur compounds or carbon
monoxide. Carbon monoxide can poison the system. A decomposition of
the membrane takes place if different grade fuels are used. Testing
and repairing a stack are difficult. The complexity to service a
fuel cell becomes apparent when considering that a typical 150V, 50
kW stack contains about 250 cells.

Figure 3: 1 kW Portable fuel
cell power generator.
The PEM fuel cell is a fully
automated power system, which converts hydrogen fuel and oxygen
from air directly into DC electricity. Water is the only by-product
of the reaction. This fuel cell generator, which operates at low
pressures, provides reliable, clean, quiet and efficient power. It
is small enough to be carried to wherever power is
needed.

Courtesy of Ballard Power Systems Inc.
[February 2001]

The Solid Oxide Fuel Cell (SOFC) is best suited for stationary
applications. The system requires high operating temperatures
(about 1000°C). Newer systems are being developed which can run
at about 700°C.

A significant advantage of the SOFC is its leniency to fuel. Due
to the high operating temperature, hydrogen is produced through a
catalytic reforming process. This eliminates the need for an
external reformer to generate hydrogen. Carbon monoxide, a
contaminant in the PEM systems, is a fuel for the SOFC. In
addition, the SOFC system offers a fuel efficiency of
60 percent, one of the highest among fuel cells.

Higher stack temperatures demand specialized and exotic
materials, which adds to manufacturing costs. Heat also presents a
challenge for longevity and reliability because of increased
material oxidation and stress. However, high temperatures offer a
benefit by enabling co-generation by running steam generators. This
improves the overall efficiency of this fuel cell system.

The Alkaline Fuel Cell (AFC) has received renewed interest
because of low operating cost. Although larger in physical size
than the PEM system, the alkaline fuel cell has the potential of
lower manufacturing and operating costs. The water management is
simpler, no compressor is usually needed, and the hardware is
cheaper. Whereas the separator for the PEM stack costs between $800
and $1,100US per square meter, the equivalent of the alkaline
system is almost negligible. (In comparison, the separator of a
lead acid battery is $5 per square meter.) Operating costs of $100
to 200 per kW are feasible. Start and stop (wetting and drying) is
more forgiving than with most other systems.

As a negative, the ALFC needs pure oxygen and hydrogen to
operate. The amount of carbon dioxide in the air can poison the
alkaline fuel cell. It should be noted, however, that carbon
dioxide is easier to scrub than carbon monoxide, a deterrent of the
PEM system.

Applications — The fuel cell is being considered as
an eventual replacement for the internal combustion engine for
cars, trucks and buses. Major car manufacturers have teamed up with
fuel cell research centers or are doing their own development.
There are plans for mass-producing cars running on fuel cells.
Because of the low operating cost of the combustion engine, and
some unresolved technical challenges of the fuel cell, however,
experts predict that a large scale implementation of the fuel cell
to power cars will not occur before 2015, or even 2020.

Large power plants running in the 40,000 kW range will likely
out-pace the automotive industry. Such systems could provide
electricity to remote locations within 10 years. Many of these
regions have an abundance of fossil fuel that could be utilized.
The stack on these large power plants would last longer than in
mobile applications because of steady use, even operating
temperatures and absence of shock and vibration.

Residential power supplies are also being tested. Such a unit
would sit in the basement or outside the house, similar to an
air-conditioning unit of a typical middle class North American
home. The fuel would be natural gas or propane, a commodity that is
available in many urban settings.

Fuel cells may soon compete with batteries for portable
applications, such as laptop computers and mobile phones. However,
today’s technologies have limitations in meeting the cost and
size criteria for small portable devices. In addition, the cost per
watt-hour is less favorable for small systems than large
installations.

Let’s examine once more the cost to produce one kilowatt
(kW) of power. In Figure 3 we learned that the investment to
provide 1kW of power using rechargeable batteries is around
$7000US. This calculation is based on 7.2V; 1000mAh NiCd packs
costing $50 each. High energy-dense batteries that deliver fewer
cycles and are more expensive than the NiCd will double the
cost.

The high cost of portable power opens vast opportunities for the
portable fuel cell. At an investment of $3,000 to $7,500 to produce
one kilowatt of power, however, the energy generated by the fuel
cell is only marginally less expensive than that produced by
conventional batteries.

Direct Methanol (DMFC), the fuel cell designed for portable
applications, would not necessarily replace the battery in the
equipment but serve as a charger that is carried separately. The
feasibility to build a mass-produced fuel cell that fits into the
form factor of a battery is still a few years away.

The advantages of the portable DMFC is: relatively high energy
density (up to five times that of a Li-ion battery); liquefied fuel
as energy supply, environmentally clean, fast recharge and long
runtimes. In fact, continuous operation is feasible. Miniature fuel
cells have been demonstrated that operate at an efficiency of 20
percent and run for 3000 hours before a stack replacement is
necessary. There is some degradation during the service life of the
fuel cell. Portable fuels cells are still in experimental
stages.

Advantages and limitations of the fuel cell — A
less known limitation of the fuel cell is the marginal loading
characteristic. On a high current load, mass transport limitations
come into effect. Supplying air instead of pure oxygen aggregates
this phenomenon.

The issue of mass transport limitation is why the fuel cell
operates best at a 30 percent load factor. Higher loads reduce the
efficiency considerably. In terms of loading characteristics, the
fuel cell does not match the performance of a NiCd battery or a
diesel engine, which perfrom well at a 100 percent load factor.

Ironically, the fuel cell will not eliminate the chemical battery
— but promote it. Similar to the argument that the computer
would make paper redundant, the fuel cell needs batteries as
a buffer. For many applications, a battery bank will provide
momentary high current loads and the fuel cell will serve to keep
the battery fully charged. For portable applications, a
supercapacitor will improve the loading characteristics and enable
high current pulses.

Most fuel cells are still handmade and are used for experimental
purposes. Fuel cell promoters remind the public that the cost will
come down once the cells are mass-produced and lower cost material
are found. While an internal combustion engine requires an
investment of $35 to $50 to produce one kilowatt (kW) of power, the
equivalent cost in a fuel cells is still a whopping $3,000 to
$7,500. The goal is a fuel cell that would cost equal or less than
diesel engines.

Summary

The fuel cell will find applications that lie beyond the reach
of the internal combustion engine. Once low cost manufacturing is
feasible, this power source will transform the world and bring
great wealth potential to those who invest in this technology.

It is said that the fuel cell is as revolutionary in
transforming our technology as the microprocessor has been. Once
fuel cell technology has matured and is in common use, our quality
of life will improve and the environmental degradation caused by
burning fossil fuel will be reversed. It is generally known that
the maturing process of the fuel cell will not be as rapid as that
of microelectronics.

This article contains excerpts from the second edition book
entitled Batteries in a Portable World — A Handbook on
Rechargeable Batteries for Non-Engineers. In the book, Mr. Buchmann
evaluates the battery in everyday use and explains their strength
and weaknesses in laymen’s terms. The 300-page book is
available from Cadex Electronics Inc. through This email address is being protected from spambots. You need JavaScript enabled to view it., tel. 604-231-7777
or most bookstores. For additional information on battery
technology and more detail on the book visit www.buchmann.ca.

Contributions have been made by Dr. Terrance Wong and Dr.
François Girard from the National Research Council in
Canada, as well as Dr. Karl Kordesch, co-inventor of the alkaline
battery and specialist in fuel cell technology.

About the Author
Isidor Buchmann is the founder and CEO of Cadex Electronics
Inc.in Vancouver, British Columbia, Canada. Mr. Buchmann has a
background in radio communications and has studied the behavior of
rechargeable batteries in practical, every day applications for two
decades. The author of many articles and books on battery
maintenance technology, Mr. Buchmann is a well-known speaker who
has delivered technical papers and presentations at seminars and
conferences around the world. He can be reached at Tel:
604-231-7777; Fax: 604-2317755; E-mail:
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